Concept preview. Not indexed. Facts are checked against the sources listed on each page.
Europa: the ocean under the ice
A moon of Jupiter slightly smaller than our Moon, with more water than all of Earth's oceans put together, according to current estimates.
| Radius | about 1,561 km |
|---|---|
| Discovered | January 1610, by Galileo |
| Next visitor | NASA's Europa Clipper, launched 14 October 2024, due at Jupiter in 2030 |
In human terms
- Europa is about 3,120 km across, roughly two thirds of the width of the lower 48 United States. If its ice shell is 15 to 25 km thick, that is about two Everests of ice on top of the ocean.
- Its ocean is often estimated at about twice the water in all of Earth's oceans, but that figure is inferred, not measured directly.
What we know and what we do not
Measured: we know this
- The surface is mostly water ice, young and cracked, with few craters.
- Galileo spacecraft magnetometer data show Europa responds to Jupiter's magnetic field the way a salty, electrically conductive layer would.
Inferred: we think this
- A global salty ocean lies under the ice. Most planetary scientists think so, but it is inferred, not seen.
- Ice shell thickness is estimated, with published ranges from a few km to about 30 km.
Unknown: we do not know
- Whether the ocean touches a rocky seafloor.
- Whether water plumes really erupt. Hubble hints in 2012 and 2016 are disputed.
- Whether anything lives there.
What would settle it
- Europa Clipper flybys measuring ice thickness, composition and plume activity from 2030.
- A later lander or probe to sample the surface or a plume.
Sources
NASA Europa Clipper mission page (science.nasa.gov/mission/europa-clipper). NASA Solar System Exploration: Europa. Concept preview: confirm ranges against the cited pages before launch.